[Mr Andrew]

I have never understood this implication of HUP before but I think I have just sorted it out.  As the time interval gets really small, the minimum energy change gets to be so large that a particle can't help but exist for that small moment of time.

Getting back to photons, the idea that I was trying to make clear in my previous post is that photons are not particles but a proportional measure of the amplitude (which can only be integer multiples of the minimum amplitude) of the oscillations of the SHO's in an object.  The energy of a SHO is E = kA²/2 = nhν.  The 'quantization' here is in the energy of an oscillation and so I am puzzled over how you can take this concept and make the leap to a 'quantization' in an electric field, which may very well not be oscillating.  It seems to me that all of the different things that have been found to be 'quantized' involve oscillations...energy of light, energy levels of electrons (standing waves) in atoms, etc.  Are you implying that electric fields are always non-constant, that they are always oscillating even if they are produced from a static charge?

[Soul Surfer]

Fields on their own can be static like gravitation and electrical.  It is only when other objects MOVE in fields that you get the interaction that involves quantised energy packets like photons.

Going back right to the beginning of this discussion. Remember that physicists were strudying why and how warm bodies emitted electromagnetic radiation.  We live in a dynamic universe and even the atoms of apparantly solid bodies are moving and jostling about  (even at the absolute zero of temperature)

[Mr Andrew]

I realize that...I even think I posted to the effect that there is no stationary magnetic field.  But of course, theory and practice are not always the same.  We can postulate about a stationary field and then extrapolate to changing fields.  I am going to read more about QED but, mostly to answer the question of how energy packets come into play in motion that might not be harmonic (like current through a static field).  Do they?, I am just thinking of different situations where things move in static fields.  Is it all motion through a static field that involves quanta?

[lightarrow]

I have never understood this implication of HUP before but I think I have just sorted it out.  As the time interval gets really small, the minimum energy change gets to be so large that a particle can't help but exist for that small moment of time.

Getting back to photons, the idea that I was trying to make clear in my previous post is that photons are not particles but a proportional measure of the amplitude (which can only be integer multiples of the minimum amplitude) of the oscillations of the SHO's in an object.  The energy of a SHO is E = kA²/2 = nhν.  The 'quantization' here is in the energy of an oscillation and so I am puzzled over how you can take this concept and make the leap to a 'quantization' in an electric field, which may very well not be oscillating.  It seems to me that all of the different things that have been found to be 'quantized' involve oscillations...energy of light, energy levels of electrons (standing waves) in atoms, etc.  Are you implying that electric fields are always non-constant, that they are always oscillating even if they are produced from a static charge?

Unfortunately I cannot say to know QED; I only know that in this theory the fields themselves are quantized, they are made of photons; so there is no need of oscillations of any kind.

[Mr Andrew]

Except that photons are the packets of oscillatory energy that a harmonic oscillator has.  Photons are not objects but are like Joules: they are units of energy (the conversion factor is hν J = 1 photon).  Saying that electric fields are made of photons is like saying it is made of cubits or seconds...preposterous.  Of course, I understand that I am the last person to claim he understands QED but if this is the conclusion of the theory, it can't be valid.  Maybe someone can explain the theory better...it is an experimentally proven theory (accurate to 10^-12 according to Wikipedia).  I still think that anything that is quantized has to have something to do with a SHO just as every SHO's energy is quantized.

[Soul Surfer]

I am not quite certain what you mean when you use the term SHO but it looks likely that you mean simple harmonic oscillator.  This is a simplification of what is going on because photons do start and stop and for a quantum to be a wave packet it must contain a range of frequencies  it is possible for some quanta of electromagnetic radiation to be extremely broad band like impulses.

[JP]

Except that photons are the packets of oscillatory energy that a harmonic oscillator has.  Photons are not objects but are like Joules: they are units of energy (the conversion factor is hν J = 1 photon).  Saying that electric fields are made of photons is like saying it is made of cubits or seconds...preposterous.  Of course, I understand that I am the last person to claim he understands QED but if this is the conclusion of the theory, it can't be valid.  Maybe someone can explain the theory better...it is an experimentally proven theory (accurate to 10^-12 according to Wikipedia).  I still think that anything that is quantized has to have something to do with a SHO just as every SHO's energy is quantized.

One way of quantizing the free electromagnetic field is by defining the same creation and annihilation operators that is used in the quantum SHO (I also think this same technique works for quantum fields in general, but I've learned it with respect to E&M).  Using a "creation" operator on a state give you an extra hbar*ω or energy (which corresponds to one 'photon').  Using an "annihilation" operator on a state takes away this same amount.  In that way, you can make units of energy, which are associated with photons. 

Why are these "particles"?  I think it's because if you go to measure a photon, you're actually measuring a packet of energy from the field.  The way a detector acts on the field is to usually annihilate some energy from the field (destroy a photon).  In this way, single photons can be "absorbed" by the detector, and they're kind of like particles. 

It's wrong to say that these photons are like "Joules."  A Joule is a unit of measurement.  These SHO states are wave functions, and physicists are used to describing particles by wave functions, so what's the problem with interpreting photons the same way?

[Alan McDougall]

No one tried to answer What is a graviton, so I will give it a bash

Graviton is a postulated quantum, or carrier of the gravitational field, analogous to the well-established photon of the electromagnetic field. Gravitons, like photons, would be travelling at the speed of light and would be emitted only by highly accelerating, extremely massive objects such as stars. Graviton is postulated to be its own antiparticle, to have zero charge and rest mass, and a spin of 2. Since gravitons are apparently identical to their antiparticles, the notion of antigravity is questionable